Commercial detonator



June 26, 1951 c, HALL 2,558,134

COMMERCIAL DETONATOR Filed Jan. 6. 1948 ATTORNEYS.

Patented June 26, 1951 COMlVIERCIAL DETONATOR Cecil B. L. Hall, Saltcoats, Scotland, assignor to Imperial Chemical Industries Limited, a corporation of Great Britain Application January 6, 1948, Serial N0. 162 In Great Britain March 5, 1947 Claims. (Cl. 102-27) The present invention relates to commercial detonators adapted to be initiated by means of a fuze. The invention relates particularly to commercial detonators having a metal casing of internal diameter lying between 0.2 inch and 0.35 inch.

The diameter of the fuze normally used with commercial detonators is only slightly less than the internal diameter of the detonator tube. Consequently the fuze can be inserted into the detonator and retained in position by a com paratively slight deformation of the tube produced by means of a crimper. Typical values for internal diameter of tube and external diameter of fuze are 0.227 inch and 0.191 inch respectively, leaving a clearance of approximately 0.018 inch.

Fuze having a considerably reduced diameter relative to the internal diameter of the detonator, i. e. a diameter lying between 0.070 inch and 0.130 inch cannot be retained satisfactorily in the normal commercial detonators by the normal crimping practice.

The object of the present invention is to provide a commercial detonator having a metal casing of internal diameter lying between 0.2 inch and 0.35 inch in which the space in the casing unoccupied by the explosive charge is so modified as particularly to permit the detonator to be used efliciently and conveniently with the said fuze of reduced diameter.

.A commercial detonator according to the present invention comprises a metal casing closed at one end and open at the other and having an internal diameter not less than 0.2 inch, wherein the closed end portion is provided with explosive material, and wherein the rest of the casing is provided with an internal sleeve having an internal diameter lying between 0.075 inch and 0.140 inch.

The internal sleeve is of comparatively soft material as for example paper, soft vulcanised rubber, synthetic rubber. This is to avoid any undue frictional effect on the explosive composition and to permit transmission of the crimp pressure to the fuze inserted into the detonator of the invention. The internal sleeve has an ex ternal diameter only slightly less than the internal diameter of the detonator tube and an internal diameter slightly greater than the external diameter of the fuze of reduced diameter the detonator of the invention is adapted to accommodate. The length of the sleeve is slightly less than the unturned and unnicked length of that part of the metal casing which is free from in the metal casing so as to be in contact with the surface of the explosive charge and is held in position by a very short length of the detonator tube which is turned over or nicked.

With a detonator according to the invention fuze of reduced diameter corresponding to the particular internal diameter of the sleeve can be inserted and retained in position by applying a crimp to the detonator tube in the normal manner. A very satisfactory waterproof joint may thus be obtained.

By way of example the following table gives typical dimensions for a detonator according to the invention which can be used with fuze of 0.120 inch diameter.

All dimensions are in inches.

By way of example the invention is illustrated in the diagrammatic drawing accompanying the specification whereof Fig. 1 is a longitudinal section of a detonator according to the invention and Fig. 2 is a longitudinal section through a detonator according to the invention shewing fuze of reduced diameter accommodated and crimped therein.

Referring to the drawing, I is a detonator metal casing, 2 is the explosive charge, 3 is an internal sleeve of paper, 4 is the turned over short metal portion of the casing I, 5 is a fuze of reduced diameter inserted into the internal sleeve 3 and held in position by the deformations l in the sleeve 3 produced by the crimp 6 given to the metal casing I.

I claim:

1. A commercial detonator comprising a metal casing tube closed at one end and opened at the other end, the closed end portion of said casin tube having an explosive material packed therein, the major portion of the remainder of said casing having an internal cylindrical sleeve of relatively soft material positioned wholly within the same in contact with the surface of the explosive charge and held in position by an upset portion at the opened end of said tube, said sleeve being adapted for receiving a reduced diameter explosive. The internal sleeve is positioned withas safety fuse.

2 A commercial detonator as set forth in claim 1 wherein the said internal sleeve is paper.

3. A commercial detonator as set forth in claim 1 wherein the said internal sleeve is soft vulcanized rubber.

4. A commercial detonator as set forth in claim 1 wherein the said internal sleeve is synthetic rubber.

5. A commercial detonator as set forth in claim 1 wherein the internal sleeve has an internal diameter slightly greater than the external diameter oi the fuseof reduced diameter that the detonator is adapted to accommodate.

CECIL R. L. HALL.

REFERENCES CITED The following references are of record in the file of this patent:

Number 10 Number 4 UNITED STATES PATENTS Name Date Bloem June 3, 1879 Williamson May 8, 1900 Keith et a1 May 30, 1905 McEachern Aug. 28, 1906 Scherrer Oct. 21, 1947 FOREIGN PATENTS Country Date Great Britain 1895 Switzerland Mar. 27, 1910 France Apr. 25, 1910 

